Lubricating oil



. is often too low for satisfactor the equilibrium viscosity Patented June 24, 1930 PATENT OFFICE m mcovu, m, 0! INGL'IWOOD, NEW

GOIIAIY, OI nw YORK, H. Y.,

nmsmr, ASSIGNOB 'ro m: mm

A OOH-203L110! OI DELAWARE LUBBIOAYIING OIL This invention relates to lubricating oils suitable for the lubrication of internal combustion engines and particularly to a lubricant adapted to substantiall maintain its viscosity during use and to equately lubricate the engine parts.

It is a common observation that the lubricating oil used in a recirculating system of a conventional internal combustion engine, employing commercial liquid fuels, such as gasoline or kerosene, becomes diluted with the fuel. This eifects a reduction in the viscosit of the oil and depreciates its value as a In ricant. It has also been observed that this contamination continues at a decreasin rate until a state of equilibrium is reache after which the viscosity of the oil in the crank case remains substantially constant. Under this latter condition the rate of eva oration of the fuel dissolved in the oil is elieved to be substantially equal to the rate at which the fuel asses the pistons of the engine and enters the lubricating oil. This rate of evaporation would increase with the concentration of the fuel in the oil and with the temperature of the crank case. In other words, one method for controlling the extent of dilution of the lubricating oil with fuel is to maintain the crank case of the engine at a selected temperature. Observations bearing on these facts have been disclosed and proven by experiments described in an article entitled Consumption and dilution of automobile engine oils, S. A. E. Journal, July, 1924, by Neil MacCoull.

Unfortunately, this equilibrium lubrication of an engine, unless the oil use was originally of such high viscosity as to have interfered with the proper flow of oil in the lubricatin system until it had been in service a sufiicient len th of time to have acquired a quantity of t e fuel diluent. This particularly true when an engine is first started during cold weather.

During investigations based on the fore-' going premises, it has been found, therefore, that if an oil of high viscosity is brought into a state that corresponds approximately to efore it is put viscosity- Application fled AIlllllt 18, ms. Serial Io. 889,881. i

into an long perio viscosity or at the most a very s 'ghtly dechnmg viscosity.

A numberless variety of oils may be prepared in accordance with the foregoin suggestlons, the broad princi le of whic consists m an oil repar b blending a comparatively hig vlscosity ubricating oil with a low boiling distillate in such proportions that the viscosity of the blended oil experiences no sharp changes in use. In common with the usual motor oils, such blended oils are usuall made with the object of attainfi a desired viscosity. In order to provide t orough and eflicient lubrication, it is desirable to incorporate in such blended oils a small amount of a material having exceptionall high lubricating value. An example of suc material is a specially prepared oxidized paraflin wax which is substantially free from gummy and other materals insoluble in t e blended motor oil. These oxidized hydrocarbons have been found to have exceptional lubricating properties and have been found in general to greatly improve the lubricating value of ordinary lubricating oils by blending. a small amount of these oil-soluble oxidized hydrocarbons in them. Although I prefer to use the material derived from a limited oxidation of paraffin wax for incorporating with oil, other oxidized hydrocarbons of the paraflin series, particularly of the more come, the latter may be run for .plex higher boiling, highly viscous and semi-solid hydrocarbons ma be employed.

In order to more fully il ustrate my invention, but without limiting effect thereon, the following example is given:

A lubricating oil having a Saybolt viscosity of about 500 sec. at 100 F. may be prepared by blending a naphthene base lubricating 011 of about "1700 sec. Saybolt viscosity at 100 F. with a light distillate whose distillation range lies between about 310 F. and 420 F. in the roportion of about 91 parts by volume of eavy oil to 9 parts by volume of distillate. To this blended oil may be added a small proportion of oxidized parafiin wax in the proportion of about 2%.

with a comparativel uniform Larger quantities of the oxidized wax may be used if desired but I prefer to use very small quantities since these have been proven sufficient to give the desired results. The oxidized wax will blend without difliculty in the lubricating oil and will not separate out even at comparatively low temperatures.

To facilitate the blending, however, it may be desirable to dissolve the oxidized wax in the light distillate prior to blending the distillate with the heavy oil. An oil blended as thus indicated, will have a flash point of about 185 F. and a Saybolt viscosity of about 500 sec. at 100 F.

For the preparation of a lubricating 011 having a Saybolt viscosity of 300 sec. at 100 F., I may employ the same lubricating oil and the light distillate, but in the proportion of 88 parts by volume of lubricating oil to 12 parts by volume of the distillate containing the desired amount of oxidized parafiin wax. Such an oil will have a flash point of about 170 F.

The other standard viscosity engine lubricating oils may similarly be prepared by employing a lower or higher viscosity base lubricant or a lesser or greater amount of diluent. Satisfactory lubricants may be made in accordance with my invention by blending lubricating oils having a Saybolt viscosity as high as 3000 see. with diluents boiling over a range from 300 F. to 500 F. and containing the desired amount ofoxidized wax.

My new lubricant is to be distinguished from previously used motor oils containing oxidized paraffin wax and which may have acquired a certain dilution, as hereinbefore explained, by the dissolving of the fuel in the lubricant during use. I therefore employ in certain of the following claims the term unused to indicate this differentiation and the term is to be construed in the claims as here indicated.

Oxidized paraffin wax for blending may be prepared for example as follows:

A charge of crude scale paraffin wax, or if desired, more refined wax, is placed in an enamel Or aluminum vessel which is preferably jacketed or otherwise fitted to permit accurate control of the temperature of the contents. Air is introduced in fine streams near the bottom of the heated wax maintained at temperatures between 260 and 330 F., preferably between 315 and 320 F. The oxidation is carried on until the acid value indicated by samples withdrawn for test is found to be about 35 and preferably not to exceed 40. Upon cooling this material, it will solidify and is found to have a light yellow color and when rubbed between the fingers has a greasy feeling.

If the oxidation has been carried out properly, the oxidized material will be found to be completely soluble in the previously mentioned light distillate and in the lubricating oil blend and will not deposit gummy or insoluble substances on standing.

Instead of employing paraffin wax as the starting material for oxidation, some of the heavier liquid or semi-liquid parafiin hydrocarbons may be employed after suitable refining and purifying treatment preferably with concentrated sulphuric acid. Li uid oils thus refined have been found to rea ily oxidize to produce materials similar in character to that derived from the oxidation of parafiin wax.

I am aware of previous sug estions to the use of lubricating oils blende with a light distillate as suggested in Wilson Patent No. 1,547,141, but by the use of my present invention superior results may be attained in the lubrication of internal combustion engines.

What I claim is:

1. An unused lubricating oil for internal combustion engines consisting of a lubricating oil having a viscosity equal to or higher than that normally used for the lubrication of internal combustion engines blended with a lesser amount of a hydrocarbon boiling below 500 F. and about 2% of oxidized paraflin wax. and having a relatively low decrease in viscosity during use.

2. An unused lubricating oil for internal combustion engines consisting of an oil having a viscosity of over 1000 sec. Saybolt at 100 F. blended with less than 25% by volume of a hydrocarbon oil boiling below 500 F. and about 2% of oxidized paraffin wax.

3. An unused lubricating oil for internal combustion engines characterized by having a flash point above 150 F., a Saybolt viscosity of at least 140 at 100 F., a relatively low loss in viscosity during use, and a content of between 7% and 15% of fractions boiling between about 300 F. and 460 F., and about 2% of oxidized paraffin wax.

4. An unused lubricating oil for internal combustion engines consisting of a lubricating oil having a viscosity equal to or higher than that normally used for the lubrication of internal combustion engines blended with a lesser amount of a hydrocarbon boiling below 500 F. and a small proportion of oxidized paraffin wax which is completely soluble therein, and having a relatively low decrease in viscosity during use.

5. An unused lubricating oil for internal combustion engines characterized by having a flash point above 150 F., a Saybolt viscosity of at least 140 at 100 F., a relatively low loss in viscosity during use, and a content of between 7% and 15% of fractions boiling between about 300 F. and 460 F., and a small proportion of oxidized parafiin wax which is completely soluble therein.

6. An unused lubricating oil for internal combustion engines consisting of a lubricat- 0 hand and seal this 13th day of Au st, 1928.

NEIL Mao OULL.

CERTIFICATE OF CORRECTION.

Patent No. 1,767,147. Granted June 24, 1930, to

NEIL MacCOULL. JR.

It is hereby certified that error appears in the printed specification or me above numbered patent requiring correction as follows: Page 2, lines 92 and 115, claims 1 and 4, and page 3, line 4, claim 6, after the word "hydrocarbon" insert the word "distillate"; and that the said Letters Patent should be read with these corrections therein that. the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of September, A. D. 1930.

M. J. Moore,

(Seal) Acting Commissioner of Patents. 

